The present invention relates to a system which processes compressed video data of different compression formats and to an apparatus for recording and reproducing compressed video signals of different compression formats.
In a television broadcasting station, digital video cassette recorders are used by reporters to gather news materials or the like. Then, records in the digital video cassette recorders are reviewed and edited for broadcasting.
The records are transferred to a server including a hard disk or the like having a high storage capacity. Once the data are stored in the server, they can be assessed by any computer connected to the server. It is desired in a television broadcasting station to broadcast the latest news. Therefore, it is required to transfer the records gathered in the recorder to the server as fast as possible.
Video data without compression can be transmitted between a digital video cassette recorder and a server. On the other hand, when compressed video data are transmitted, the data can be transferred if the data compression format of the digital video cassette recorder is the same as that of the main server. However, the compression format of video data such as DV format of a digital If video cassette recorder is usually different from the compression format of a server having a format such as MPEG standard. Therefore, a format converter for converting data compression format is needed between the digital video cassette recorder and the server. However, if the transfer speed of the server is normal speed, the compressed digital video data can be transferred only at the normal speed from the digital video cassette recorder. Therefore, speed cannot be increased even if the recorder can reproduce the data at a faster speed. It is desirable to construct a system which can deal with video data at a fast speed even if various data compression formats are used therein.
An object of the present invention is to provide a compressed video data processing system and an apparatus therefor which can satisfy compatibility of compressed digital video data of two or more different image compression formats.
Another object of the present invention is to provide a compressed video data processing system and an apparatus therefor which can record or reproduce compressed video data at a high speed even if conversion between two or more different image compression formats are processed.
In one aspect of the invention, a compressed video data processing system comprises a digital video cassette recorder for recording and reproducing video data according to a first image compression format, a first recording and reproducing device as a local server, and an image format converter connected between the digital video cassette recorder and the first recording and reproducing device. Further, the first recording and reproducing device as a local server is connected to a second recording and reproducing device as a main server. The first and second recording and reproducing devices record and reproduce compressed digital video data according to a second image compression format different from the first image compression format. The image format converter converts compressed digital video data between the first image compression format and the second image compression format. The second recording and reproducing device may be accessed by computers through a network. By providing the first recording and reproducing device between the image format converter and the second recording and reproducing device, the second recording and reproducing device can operate normally even when accessed by many computers.
In another aspect of the invention, a compressed video data processing system comprises a digital video cassette recorder, a first recording and reproducing device as a local server connected to the digital video cassette recorder, a second recording and reproducing device as a main server, an image format converter connected between the first and second recording and reproducing device. The digital video cassette recorder and the first recording and reproducing device record and reproduce video data according to a first image compression format, while the second recording and reproducing device record and reproduce video data according to a second image compression format. The image format converter converts compressed digital video data between the first and second image compression formats. Compressed video data are transferred between the digital video cassette recorder and the first recording and reproducing device at a first transfer speed, while compressed digital video data are transferred in a network transmission format between the first and second recording and reproducing devices through the image format converter at a second transfer speed. The first recording and reproducing apparatus can record and reproduce data at either of the first and second transfer speeds. Then, even if video data of the first and second image compression formats are not compatible with each other, compressed digital video data according to the first image compression format can be converted to those according to the second one, and vice versa. Thus, video data of different compression formats can be used easily in a single system. The first transfer speed can be determined independently of the second transfer speed. It is preferable that the second transfer speed is faster than the first transfer speed in order to transfer the data in the digital video cassette recorder at a high transfer speed in a form accessed in the first recording reproducing device.
Preferably, the image format converter may support a plurality of conversion processes between the first image compression format and one of a plurality of the second image compression formats for the main server. In the image format converter, a format detector detects the second image compression format and selects one of the conversion processes automatically according to the second image compression format detected by the image format converter. Thus, a user can use video data without knowing the image compression format.
In order to support a plurality of the first image compression formats, a plurality of combinations of the first recording and reproducing device and the compression format converter are preferably provided, each of the combinations corresponding to one of the plurality of the first image compression formats. Then, compressed digital video data according to the first image compression format of two or more different conversion speeds can be converted to each other. Preferably, the first recording and reproducing device comprises a plurality of input/output ports for compressed digital video data according to the first image compression format. Then, a plurality of compressed digital video data according to the first image compression format can be output or input efficiently. Preferably, the second recording and reproducing means comprises a plurality of input/output ports for compressed digital video data according to the second image compression format. Then, a plurality of compressed digital video data according to the second image compression format can be output input efficiently.
Components in the system can be integrated as an apparatus. For example, a compressed video data processing apparatus comprises the digital video cassette recorder, the first recording and reproducing device and the image format converter. In a different example, a compressed video data processing apparatus comprises the first recording and reproducing device and the image format converter. Thus, a user can deal with video data easily without knowing conversion of image compression format. In these examples, the digital video cassette recorder is connected to the apparatus as an external component.
An advantage of the present invention is that the second recording and reproducing device as a main server can operate normally when video data of the first image compression format different from the image compression format thereof are recorded or reproduced after conversion of the image compression format.
Another advantage of the present invention is that video data can be transferred at a fast speed to the first recording and reproducing device.
A further advantage of the present invention is that a system can comprise components of various image compression formats.